README

performance_test

[TOC]

The performance_test tool tests latency and other performance metrics of various middleware implementations that support a pub/sub pattern. It is used to simulate non-functional performance of your application.

The performance_test tool allows you to quickly set up a pub/sub configuration, e.g. number of publisher/subscribers, message size, QOS settings, middleware. The following metrics are automatically recorded when the application is running:

• latency: corresponds to the time a message takes to travel from a publisher to subscriber. The latency is measured by timestamping the sample when it’s published and subtracting the timestamp (from the sample) from the measured time when the sample arrives at the subscriber (only logged when a subscriber is created)

• CPU usage: percentage of the total system wide CPU usage (logged separately for each instance of perf_test)

• resident memory: heap allocations, shared memory segments, stack (used for system’s internal work) (logged separately for each instance of perf_test)

• sample statistics: number of samples received, sent, and lost per experiment run.

This master branch is compatible with the following ROS 2 versions

• rolling

• jazzy

• iron

• humble

• galactic

• foxy

• eloquent

• dashing

• Apex.OS

How to use this document

1. Start here for a quick example of building and running the performance_test tool with the Cyclone DDS plugin.

2. If needed, find more detailed information about building and running

3. Or, if the quick example is good enough, skip ahead to the list of supported middleware plugins to learn how to test a specific middleware implementation.

4. Check out the tools for visualizing the results

5. If desired, read about the design and architecture of the tool.

Example

This example shows how to test the non-functional performance of the following configuration:

Option	Value
Plugin	Cyclone DDS
Message type	Array1k
Publishing rate	100Hz
Topic name	test_topic
Duration of the experiment	30s
Number of publisher(s)	1 (default)
Number of subscriber(s)	1 (default)

1. Install ROS 2

2. Install Cyclone DDS to /opt/cyclonedds

3. Build performance_test with the CMake build flag for Cyclone DDS:

   source /opt/ros/rolling/setup.bash
   cd ~/perf_test_ws
   colcon build --cmake-args -DPERFORMANCE_TEST_PLUGIN=CYCLONEDDS
   source ./install/setup.bash
   

4. Run with the communication plugin option for Cyclone DDS:

mkdir experiment
./install/performance_test/lib/performance_test/perf_test --communication CycloneDDS
                                                          --msg Array1k
                                                          --rate 100
                                                          --topic test_topic
                                                          --max-runtime 30
                                                          --logfile experiment/log.csv

At the end of the experiment, a CSV log file will be generated in the experiment folder with a name that starts with log.

Building the performance_test tool

For a simple example, see Dockerfile.rclcpp.

The performance_test tool is structured as a ROS 2 package, so colcon is used to build it. Therefore, you must source a ROS 2 installation:

source /opt/ros/rolling/setup.bash

Select a middleware plugin from this list. Then build the performance_test tool with the selected middleware:

mkdir -p ~/perf_test_ws/src
cd ~/perf_test_ws/src
git clone https://gitlab.com/ApexAI/performance_test.git
cd ..
# At this stage, you need to choose which middleware you want to use
# The list of available flags is described in the middleware plugins section
# Square brackets denote optional arguments, like in the Python documentation.
colcon build --cmake-args -DCMAKE_BUILD_TYPE=Release -DPERFORMANCE_TEST_PLUGIN=<plugin>
source install/setup.bash

Running an experiment

The performance_test experiments are run through the perf_test executable. To find the available settings, run with --help (note the required and default arguments):

~/perf_test_ws$ ./install/performance_test/lib/performance_test/perf_test --help

• The -c argument should match the selected middleware plugin from the build phase.

• The --msg argument should be one of the supported message types, which are shown in the --help output.

Single machine or distributed system?

Based on the configuration you want to test, the usage of the performance_test tool differs. The different possibilities are explained below.

For running tests on a single machine, you can choose between the following options:

1. Intraprocess means that the publisher and subscriber threads are in the same process.

   perf_test <options> --num-sub-threads 1 --num-pub-threads 1
   

2. Interprocess means that the publisher and subscriber are in different processes. To test interprocess communication, two instances of the performance_test must be run, e.g.

   # Start the subscriber first
   perf_test <options> --num-sub-threads 1 --num-pub-threads 0 &
   sleep 1  # give the subscriber time to finish initializing
   perf_test <options> --num-sub-threads 0 --num-pub-threads 1
   

On a distributed system, testing latency is difficult, because the clocks are probably not perfectly synchronized between the two devices. To work around this, the performance_test tool supports relay mode, which allows for a round-trip style of communication:

# On the main machine
perf_test <options> --roundtrip-mode Main

# On the relay machine:
perf_test <options> --roundtrip-mode Relay

In relay mode, the Main machine sends messages to the Relay machine, which immediately sends the messages back. The Main machine receives the relayed message, and reports the round-trip latency. Therefore, the reported latency will be roughly double the latency compared to the latency reported in non-relay mode.

Single machine, single thread

An intra-thread configuration is experimentally supported, in which a publisher and subscriber both operate in the same thread. The publisher writes a messages, and the subscriber immediately takes it.

perf_test <options> -e INTRA_THREAD

Notes:

1. This is only available when zero copy transfer is enabled

2. This requires exactly one publisher and one subscriber

3. This is not compatible with roundtrip mode

Middleware plugins

The performance test tool can measure the performance of a variety of communication solutions from different vendors. In this case there is no rclcpp or rmw layer overhead over the publisher and subscriber routines.

The performance_test tool implements an executor that runs the publisher(s) and/or the subscriber(s) in their own thread.

The following plugins are currently implemented:

Eclipse Cyclone DDS

• Eclipse Cyclone DDS 0.9.0b1

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=CYCLONEDDS

• Communication plugin: -c CycloneDDS

• Docker file: Dockerfile.CycloneDDS

• Available transports:

  • Cyclone DDS zero copy requires RouDi to be running.

  • Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
    INTRA (default), SHMEM (--shared-memory), LoanedSamples (--zero-copy)	UDP (default), SHMEM (--shared-memory), LoanedSamples (--zero-copy)	UDP

Eclipse Cyclone DDS C++ binding

• Eclipse Cyclone DDS C++ bindings 0.9.0b1

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=CYCLONEDDS_CXX

• Communication plugin: -c CycloneDDS-CXX

• Docker file: Dockerfile.CycloneDDS-CXX

• Available transports:

  • Cyclone DDS zero copy requires the RouDi to be running.

  • Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
    INTRA (default), SHMEM (--shared-memory), LoanedSamples (--zero-copy)	UDP (default), SHMEM (--shared-memory), LoanedSamples (--zero-copy)	UDP

Eclipse iceoryx

• iceoryx (latest master as of Feb 13)

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=ICEORYX

• Communication plugin: -c iceoryx

• Docker file: Dockerfile.iceoryx

• The iceoryx plugin is not a DDS implementation.

  • The DDS-specific options (such as domain ID, durability, and reliability) do not apply.

• To run with the iceoryx plugin, RouDi must be running.

• Available transports:

  Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
  LoanedSamples	LoanedSamples	Not supported by performance_test

eProsima Fast DDS

• FastDDS 2.6.2

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=FASTDDS

• Communication plugin: -c FastRTPS

• Docker file: Dockerfile.FastDDS

• Available transports:

  Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
  INTRA (default), LoanedSamples (--zero-copy)	SHMEM (default), LoanedSamples (--zero-copy)	UDP

OCI OpenDDS

• OpenDDS 3.13.2

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=OPENDDS

• Communication plugin: -c OpenDDS

• Docker file: Dockerfile.OpenDDS

• Available transports:

  Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
  TCP	TCP	TCP

RTI Connext DDS

• RTI Connext DDS 5.3.1+

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=CONNEXTDDS

• Communication plugin: -c ConnextDDS

• Docker file: Not available

• A license is required

• You need to source an RTI Connext DDS environment.

  • If RTI Connext DDS was installed with ROS 2 (Linux only):

    • source /opt/rti.com/rti_connext_dds-5.3.1/setenv_ros2rti.bash

  • If RTI Connext DDS is installed separately, you can source the following script to set the environment:

    • source <connextdds_install_path>/resource/scripts/rtisetenv_<arch>.bash

• Available transports:

  Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
  INTRA	SHMEM	UDP

RTI Connext DDS Micro

• Connext DDS Micro 3.0.3

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=CONNEXTDDSMICRO

• Communication plugin: -c ConnextDDSMicro

• Docker file: Not available

• A license is required

• Available transports:

  Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
  INTRA	SHMEM	UDP

Framework plugins

The performance_test tool can also measure the end-to-end latency of a framework. In this case, the executor of the framework is used to run the publisher(s) and/or the subscriber(s). The potential overhead of the rclcpp or rmw layer is measured.

ROS 2

The performance test tool can also measure the performance of a variety of RMW implementations, through the ROS 2 rclcpp::publisher and rclcpp::subscriber API.

• ROS 2 rclcpp::publisher and rclcpp::subscriber

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=ROS2 (default)

• Communication plugin:

  • Callback with Single Threaded Executor: -c rclcpp-single-threaded-executor

  • Callback with Static Single Threaded Executor: -c rclcpp-static-single-threaded-executor

  • rclcpp::WaitSet: -c rclcpp-waitset

• Docker file: Dockerfile.rclcpp

• Available underlying RMW implementations:

  • ROS 2 Rolling is pre-configured to use rmw_fastrtps_cpp

  • Follow these instructions to use a different RMW implementation

• Available transports: depends on underlying RMW implementation

  • LoanedSamples are available (--zero-copy) for ROS_DISTRO = foxy and above

Apex.OS

• Apex.OS

• CMake build flag: -DPERFORMANCE_TEST_PLUGIN=APEX_OS

  • It is also required to source /opt/ApexOS/setup.bash instead of a ROS 2 distribution

• Communication plugin: -c ApexOSPollingSubscription

• Docker file: Not available

• Available underlying RMW implementations: rmw_apex_middleware

• Available transports:

  Pub/sub in same process	Pub/sub in different processes on same machine	Pub/sub in different machines
  UDP (default), SHMEM (--shared-memory), LoanedSamples (--zero_copy)	UDP (default), SHMEM (--shared-memory), LoanedSamples (--zero_copy)	UDP

Analyze the results

After an experiment is run with the -l flag, a log file is recorded. Both CSV and JSON formats are supported. It is possible to add custom data to the log file by setting theAPEX_PERFORMANCE_TEST environment variable before running an experiment, e.g.

# JSON format
export APEX_PERFORMANCE_TEST="
{
\"My Version\": \"1.0.4\",
\"My Image Version\": \"5.2\",
\"My OS Version\": \"Ubuntu 16.04\"
}
"

Plot the results

To plot the results in the JSON or CSV log files, see the plotter README.

Architecture

Apex.AI’s Performance Testing in ROS 2 white paper (available here) describes how to design a fair and unbiased performance test, and is the basis for this project.

Each middleware has a different API. Thanks to the Plugin abstraction, the core logic of setting up and running an experiment is completely decoupled from the implementation details of sending and receiving individual messages.

Exactly one Plugin implementation is selected at build time. The design is similar to the Abstract Factory pattern. performance_test declares, but does not define, a static factory method in the PluginFactory class. Each middleware provides a definition for this factory method to create a concrete Plugin implementation, and perf_test calls this factory method directly.

An example plugin is available here.

Performance optimizations

• On linux-based platforms, perf_test writes 0 to /dev/cpu_dma_latency and holds open the file handle, which will prevent the CPU from entering any idle states for the duration of the experiment. This should result in lower message latency and lower variance in that latency.

Future extensions and limitations

• Communication frameworks like DDS have a huge amount of settings. This tool only allows the most common QOS settings to be configured. The other QOS settings are hardcoded in the application.

• Only one publisher per topic is allowed, because the data verification logic does not support matching data to the different publishers.

• Some communication plugins can get stuck in their internal loops if too much data is received. Figuring out ways around such issues is one of the goals of this tool.

• FastRTPS wait-set does not support timeouts which can lead to the receiving not aborting. In that case the performance test must be manually killed.

• Using Connext DDS Micro INTRA transport with reliable QoS and history kind set to keep_all is not supported with Connext Micro. Set keep-last as QoS history kind always when using reliable.

Possible additional communication which could be implemented are:

• Raw UDP communication

Building with limited resources

When building this tool, the compiler must perform a lot of template expansion. This can be overwhelming for a system with a low-power CPU or limited RAM. There are some additional CMake options which can reduce the system load during compilation:

1. This tool includes many different message types, each with many different sizes. Reduce the number of messages, and thus the compilation load, by disabling one or more message types. For example, to build without PointCloud messages, add -DENABLE_MSGS_POINDCLOUD=OFF to the --cmake-args. The message types, and their options for enabling/disabling, can be found here.